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View Full Version : Using automotive 4.3L in marine application?



Hubjeep
02-01-2007, 10:27 AM
Howdy all,
I am still throwing around engine options for my 1990 GT210 Donzi. The original 4.3L OMC V6 needs to be replaced. I have yet to pull it out and assess the feasibility of a rebuild, but would like to discuss my options.

From what I hear from a number of people, a 4.3L (s-10 blazer?) automotive block can be used in place of a marine block once brass freeze out plugs are installed and ideally a "towing" or marine camshaft. Any idea what year blocks would work? :confused:

Another option would be to go with a V8, part of me would like to stay with the V6 since besides the block, the only other big part I will need is new manifolds and risers (don't want to risk using the rusty old ones, especially since I do not know their history). Then outdrive ratios come into play, as well as motor mounts, shift linkage, and exhaust routing.

Here is a pic of the current engine (Don't 1990's have one piece manifold/risers?)
http://img.photobucket.com/albums/v222/Hubjeep/Donzi/PICT0003-2.jpg

Thanks,
John

The Hedgehog
02-02-2007, 01:19 PM
Why not just get a bobtail v-6? They are pretty cheap.

You can marinize an auto angine pretty easy but you will need a marine carb, ignition, and cam. Use the Ebelbrock performer cam. It has a pretty good grond. Not sure if you can do that cheaper than buying a marine package.

MOP
02-02-2007, 06:11 PM
Go with the V8, reason the parts you need run almost the same price. You may want to investigate complete packages there are some very decent deals out there, the 8 is a bolt in with a simple mount position move.

Phil

NeedSpeed
02-03-2007, 10:14 AM
It depends how much time you want to put into tinkering with it.

I once replaced an 18 year old 260 Merc with a remanufactured engine and kept the existing manifolds, carb, starter, etc. Strangely enough, all of the old Merc parts turned out to be better than the Jasper long block I purchased. I spent over double the cost of the long block trying to get it to run correctly. The mechanic that made it run right said that almost always it is better to buy a Merc package from the crate that has everything (minus the drive & transom components) and be done with the expense. He was right.

So, if you want to tinker with the boat and get nickel and dimed for the next several years, a rebuilt is the route. For a turnkey solid engine that shouldn't give you any issues, I would get the Merc package. Way expensive but it should work.

As for the V8 vs. V6.......
You will be stashing shots bags all over the boat to get the balance correct. If it rides nice with the V-6, it most likely won't with a heavier V-8 in the stern. Again, if you like projects, go with the V-8.

My .02 for what it's worth.:wink:

BigGrizzly
02-04-2007, 09:01 AM
I don't think marineise a an auto engine is a bad idea I do it all the time. brass freeze plugs and a marine cam than a marine carb or fix that one. As for V8 or v6 that is your choice, I prefer the V8. However with 2 boats one a V6 with better fuel economy should be my next choice. As for balance the 16 were originally almost all V8 until late 80's or early 90's. The V8 is no more than a passenger in the back seat. Jack did his 16 boat with a V8 and thinks it is better all around. Last time I saw it it was doing well in the Gulf at the Sota rally